Under ground swimming pool modular wall structure

ABSTRACT

The modular wall structure for underground swimming pools comprises a number of wall panels each comprising an upright portion defining opposite inner and outer sides, opposite first and second edges and opposite top and bottom ends. The wall panel also has a shelf portion generally perpendicular to the upright portion and attached thereto at the top end in cantilevered fashion. The wall panel includes an inclined bracing portion linking the outer side of the upright portion to the shelf portion in an inclined fashion. The wall panel further has complementary attachment members provided on the upright portion first and second edges to allow the wall panel to be edgewisely attached at its first edge to the second edge of an adjacent the wall panel and along its second edge to the first edge of an adjacent the wall panel.

FIELD OF THE INVENTION

The present invention relates to underground swimming pools, and more particularly to a modular wall structure for underground swimming pools.

BACKGROUND OF THE INVENTION

It is known to use modular wall structures for underground swimming pools. Some known modular wall structures include a number of wall panels that are linked at their edges to form the peripheral wall of the swimming pool. Ground-resting transverse support walls or braces are further installed against the outer surface of some swimming pool wall panels, i.e. the surface that faces outside of the swimming pool. These transverse braces abut with an edge portion thereof against the flat outer surface of the wall panels, and are used to reinforce the swimming pool wall structure, but mostly their purpose is to support a horizontal deck that will rest atop the swimming pool wall panels and extend radially outwardly about the swimming pool wall panels to allow the pool users to walk thereon.

A problem with conventional swimming pool transverse braces is that they require a significant clearance to be dug around the swimming pool wall panels to accommodate the transverse braces. Consequently, it is more difficult, if not entirely impossible, to have the deck rest partly on solid ground. Indeed, even though sand or earth will be used to fill the hole outside of the wall panels around and between the transverse braces, this filling sand or earth will not be compacted as much as the naturally compacted untouched ground earth. If the concrete deck was to rest on filling sand or earth, the latter would inevitably collapse under the weight of the deck, since it is not as solid as ground that has remained untouched and that has become naturally compacted over the years.

Consequently, not only does a larger hole need to be dug around the swimming pool wall to accommodate the transverse braces, but also the installation of the transverse braces requires that these braces be strong enough to support the entire weight of the deck since the latter will be entirely supported by the braces. The production cost and the installation cost of the prior art swimming pools is consequently relatively high.

SUMMARY OF THE INVENTION

The present invention relates to a modular wall structure for underground swimming pools comprising a number of wall panels each comprising:

-   -   an upright portion defining opposite inner and outer sides,         opposite first and second edges and opposite top and bottom         ends;     -   a shelf portion generally perpendicular to said upright portion         and attached thereto at said top end in cantilevered fashion;     -   an inclined bracing portion linking said outer side of said         upright portion to said shelf portion in an inclined fashion;         and     -   complementary attachment members provided on said upright         portion first and second edges to allow said wall panel to be         edgewisely attached at its first edge to the second edge of an         adjacent said wall panel and along its second edge to the first         edge of an adjacent said wall panel.

In one embodiment, at least some of said wall panels are hollow for allowing concrete to be poured therein.

In one embodiment, said shelf and upright portions are not integrally linked, but are attached to each other, with said shelf portion resting against said upright portion along an inclined abutment surface transversal to said bracing portion, with said bracing portion being formed in part by a wall of said upright portion and in part by a wall of said shelf portion.

In one embodiment, said complementary attachment members comprise interlocking tongue and groove members comprising a first tongue on said first edge and a first groove on said second edge complementary to said first tongue, whereby said first tongue of one said wall panel can be inserted in said first groove of another said wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said first groove retaining said first tongue for preventing said one and another wall panels thus attached to each other from being pulled apart.

In one embodiment, said tongue and groove members further comprise a second tongue on said second edge and a second groove on said first edge complementary to said second tongue, whereby said second tongue of said one wall panel can be inserted in said second groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said second groove retaining said second tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.

In one embodiment, said tongue and groove members further comprise:

-   -   a third tongue on said first edge and a third groove on said         second edge complementary to said third tongue, whereby said         third tongue of said one wall panel can be inserted in said         third groove of said another wall panel when said first edge of         said one wall panel is disposed side-by-side with said second         edge of said another wall panel, with said third groove         retaining said third tongue for further preventing said one and         another wall panels thus attached to each other from being         pulled apart; and     -   a fourth tongue on said second edge and a fourth groove on said         first edge complementary to said fourth tongue, whereby said         fourth tongue of said one wall panel can be inserted in said         fourth groove of said another wall panel when said first edge of         said one wall panel is disposed side-by-side with said second         edge of said another wall panel, with said fourth groove         retaining said fourth tongue for further preventing said one and         another wall panels thus attached to each other from being         pulled apart.

In one embodiment, said first and second tongues are inwardly-oriented, said first and second grooves are outwardly-opened, said third and fourth tongues are outwardly-oriented and said third and fourth grooves are inwardly-opened.

In one embodiment, said tongue and groove members further comprise:

-   -   a fifth inwardly-oriented tongue on said first edge and a fifth         outwardly-opened groove on said second edge complementary to         said fifth tongue, whereby said fifth tongue of said one wall         panel can be inserted in said fifth groove of said another wall         panel when said first edge of said one wall panel is disposed         side-by-side with said second edge of said another wall panel,         with said fifth groove retaining said fifth tongue for further         preventing said one and another wall panels thus attached to         each other from being pulled apart; and     -   a sixth inwardly-oriented tongue on said second edge and a sixth         outwardly-opened groove on said first edge complementary to said         sixth tongue, whereby said sixth tongue of said one wall panel         can be inserted in said sixth groove of said another wall panel         when said first edge of said one wall panel is disposed         side-by-side with said second edge of said another wall panel,         with said sixth groove retaining said sixth tongue for further         preventing said one and another wall panels thus attached to         each other from being pulled apart.

In one embodiment, said first and fifth tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said first and fifth grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said second and sixth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, and said second and sixth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge.

In one embodiment, said tongue and groove members further comprise:

-   -   a seventh outwardly-oriented tongue on said first edge and a         seventh inwardly-opened groove on said second edge complementary         to said seventh tongue, whereby said seventh tongue of said one         wall panel can be inserted in said seventh groove of said         another wall panel when said first edge of said one wall panel         is disposed side-by-side with said second edge of said another         wall panel, with said seventh groove retaining said seventh         tongue for further preventing said one and another wall panels         thus attached to each other from being pulled apart; and     -   an eighth outwardly-oriented tongue on said second edge and an         eighth inwardly-opened groove on said first edge complementary         to said eighth tongue, whereby said eighth tongue of said one         wall panel can be inserted in said eighth groove of said another         wall panel when said first edge of said one wall panel is         disposed side-by-side with said second edge of said another wall         panel, with said eighth groove retaining said eighth tongue for         further preventing said one and another wall panels thus         attached to each other from being pulled apart.

In one embodiment, said third and seventh tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said third and seventh grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said fourth and eighth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, and said fourth and eighth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge.

In one embodiment, said upright portion of each said wall panels comprises at said bottom end a base with a foot member of adjustable length that is extendable away from and retractable towards said base in a direction opposite said top end.

In one embodiment, said foot member threadingly engages said base and can thus be screwed or unscrewed to adjust its length.

In one embodiment, said modular wall structure further comprises a filter wall panel comprising:

-   -   a filter panel upright portion defining opposite inner and outer         sides, opposite first and second edges and opposite top and         bottom ends;     -   a top clearance at said top end for allowing a filter to be         installed near said top end;     -   a filter opening extending through said filter wall panel near         said top end; and     -   complementary attachment members provided on said filter panel         upright portion first and second edges to allow said filter wall         panel to be edgewisely attached at its first edge to the second         edge of an adjacent said wall panel and along its second edge to         the first edge of an adjacent said wall panel.

The present invention also relates to an underground swimming pool comprising a modular wall structure comprising a number of wall panels each comprising:

-   -   an upright portion defining opposite inner and outer sides,         opposite first and second edges and opposite top and bottom         ends;     -   complementary attachment members provided on said upright         portion first and second edges to allow said wall panel to be         edgewisely attached at its first edge to the second edge of an         adjacent said wall panel and along its second edge to the first         edge of an adjacent said wall panel, whereby all said wall         panels are consecutively edgewisely attached to form a         continuous peripheral wall of said swimming pool; and     -   an inner chamber at least partly filled with concrete; wherein         at least some of said wall panels further comprise:     -   a shelf portion generally perpendicular to said upright portion         and attached thereto at said top end in cantilevered fashion;         and     -   an inclined bracing portion linking said outer side of said         upright portion to said shelf portion in an inclined fashion;         said swimming pool further comprising a flexible sheet carried         by said peripheral wall and extending within said peripheral         wall to form an enclosure for containing water, and a deck         comprising a number of deck slabs, at least some of said deck         slabs being at least partly supported by said shelf portions and         extending away from said modular wall structure for being partly         supported on the ground.

DESCRIPTION OF THE DRAWINGS

In the annexed drawings:

FIG. 1 is a cross-sectional view of one side of a swimming pool comprising the modular wall structure of the present invention, further suggesting the ground under and around the swimming pool wall structure and a deck installed about the upper end of the modular wall structure;

FIG. 2 is a perspective view of a section of the modular wall structure of the present invention including five wall panels;

FIGS. 3 and 4 are respectively inner and outer perspective views of a pair of wall panels forming the modular wall structure of the present invention, in a disassembled condition;

FIG. 5 is similar to FIG. 4, although at a smaller scale, with the wall panels in their assembled condition;

FIG. 5 a is an enlarged cross-sectional top plan view taken along line 5 a-5 a of FIG. 5;

FIG. 6 is an enlarged view of the area circumscribed by line VI of FIG. 1; and

FIG. 7 is an exploded outer perspective view of one of the wall panels of the modular wall structure section of FIG. 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a cross-section of a modular wall structure 20 of an underground swimming pool 22 according to the present invention. A hole has been conventionally made in the ground to accommodate swimming pool 22, with a dugout 24 remaining outside of wall structure 20 once the latter is installed. Dugout 24 will be as narrow as possible, but its presence is inevitable due to the space required during the assembly of modular wall structure 20. Dugout 24 is filled with earth or sand once modular wall structure is completely assembled. Outwardly of dugout 24, there remains the untouched, naturally compacted ground G.

As shown in FIGS. 1-7, modular wall structure 20 comprises a number of wall panels 26 a, 26 b, 26 c, 26 d, 26 e, 26 f, 26 g, 26 h, that will be generally referred to as wall panels 26 in the present specification. Wall panels 26 may have a slightly different configuration as described hereinafter, for example some may be curved such as panels 26 c and 26 d, some may have a filter opening 28 such as wall panel 26 a, but at least some wall panels 26 will share common characteristics as detailed hereinafter. More particularly, each wall panel according to the present invention, for example wall panel 26 f as shown in FIGS. 1 and 3-6, comprises an upright portion 30 defining opposite inner and outer sides 32, 34, opposite top and bottom ends 33, 35 and opposite first and second edges 36, 38. Wall panel 26 also comprises a shelf portion 40 generally perpendicular to upright portion 30 and attached thereto at its upper end 33 in cantilevered fashion. Shelf portion 40 defines upper and lower sides 42, 44. Wall panel 26 further comprises an inclined bracing portion 46 linking the outer side 34 of upright portion 30 to the lower side 44 of shelf portion 40 in an inclined fashion.

In the embodiment shown in the annexed drawings, the shelf portion 40 and the upright portion 30 are not integrally linked, but are rather distinctly produced and thereafter attached to each other as suggested in FIG. 7, with shelf portion 40 resting against upright portion 30 along an inclined abutment surface 48 transversal to the bracing portion 46. It can consequently be seen that bracing portion 46 is formed in part by a wall 46 a of upright portion 30 and in part by a wall 46 b of shelf portion 40 (see FIG. 6), with walls 46 a and 46 b being coextensive. However, in an alternate embodiment of the invention (not shown), upright and shelf portions 30, 40 could be made as a unitary element.

Also, wall panels 26 are hollow, for allowing concrete to be poured therein. Upright portion 30 thus comprises at least one mouth opening 50 (see FIGS. 4 and 7) to allow concrete to be poured into the inner chamber defined within the hollow main body of the wall panel upright portion. Moreover, the wall panel shelf portion 40 is also hollow and defines a through channel with at least one pair of top and bottom mouth openings 52, 54, with the shelf portion bottom mouth opening 54 communicating with the upright portion mouth opening 50 to allow concrete to be poured through the shelf portion channel and into upright portion 30. Once upright portion 30 is filled with concrete, additional concrete is added to in turn fill shelf portion 40.

Complementary attachment members are provided on the upright portion first and second edges 36, 38 of each wall panel 26, to allow a wall panel 26 to be edgewisely attached at its first edge 36 to the second edge 38 of an adjacent wall panel 26 and along its second edge 38 to the first edge 36 of an adjacent wall panel 26. This is suggested in FIGS. 2-5 and 5 a.

More particularly, the complementary attachment members comprise interlocking tongue and groove members comprising a number of tongues 56 a, 56 b, 56 c, 56 d (generally referred to with reference number 56 in the present specification) on first edge 36 and a number of grooves 58 a, 58 b, 58 c, 58 d (generally referred to with reference number 58 in the present specification) on second edge 38, with specific grooves 58 being complementary to corresponding tongues 56 for inserting these corresponding tongues 56 of an adjacent wall panel 26 therein. The tongue and groove members further comprise a number of tongues 60 a, 60 b, 60 c, 60 d (generally referred to with reference number 60 in the present specification) on second edge 38 and a number of grooves 62 a, 62 b, 62 c, 62 d (generally referred to with reference number 62 in the present specification) on first edge 36, with specific grooves 62 being complementary to corresponding tongues 60 for inserting these corresponding tongues 60 of an adjacent wall panel 26 therein. Once tongues 56 are inserted in corresponding grooves 58 of an adjacent wall panel and tongues 60 are inserted in corresponding grooves 62 of an adjacent wall panel, grooves 58 will retain tongues 56 and grooves 62 will retain tongues 60 for preventing two panels 26, 26 thus attached to each other from being separated by pulling them apart.

Specifically, panel 26 (such as panel 26 f in FIGS. 3 and 4) comprises on its first edge 36 longitudinally spaced-apart inwardly-oriented first and second tongues 56 a, 56 b, and longitudinally spaced-apart outwardly-oriented first and second tongues 56 c, 56 d; and on its second edge 38, longitudinally spaced-apart inwardly-oriented first and second tongues 60 a, 60 b, and longitudinally spaced-apart outwardly-oriented first and second tongues 60 c, 60 d. Panel 26 also comprises on its second edge 38 longitudinally spaced-apart outwardly-opened first and second grooves 58 a, 58 b that can be respectively engaged by the inwardly-oriented first edge first and second tongues 56 a, 56 b of an adjacent wall panel 26, and longitudinally spaced-apart inwardly-opened first and second grooves 58 c, 58 d that can be respectively engaged by the outwardly-oriented first edge first and second tongues 56 cc, 56 d. Panel 26 further comprises on its first edge 36 longitudinally spaced-apart outwardly-opened first and second grooves 62 a, 62 b that can be respectively engaged by the second edge inwardly-oriented first and second tongues 60 aa, 60 b of an adjacent wall panel 26, and longitudinally spaced-apart inwardly-opened first and second grooves 62 c, 62 d that can be respectively engaged by the second edge outwardly-oriented first and second tongues 58 c, 58 d of an adjacent wall panel 26.

According to the tongue and groove members 56, 58, 60, 62 of the present invention, an advantageous interlocking attachment of side-by-side panels 26 is obtained. Indeed, each edge 36, 38 of a wall panel 26 engages the other edge 38, 36 of an adjacent wall panel 26 by means of two pairs of longitudinally spaced-apart tongues—one pair of inwardly-oriented tongues and one pair of outwardly-oriented tongues—that engage respective complementary outwardly-opened and inwardly-opened grooves on the other edge; and each edge 36, 38 is likewise engaged with the tongues of the adjacent wall panel 26 in its two pairs of longitudinally spaced-apart grooves—one pair of inwardly-oriented grooves and one pair of outwardly-oriented grooves. Thus, a total of eight tongues engage eight corresponding grooves in an attachment between two adjacent wall panels. This method of attachment is advantageous since not only does it prevent disengagement of the wall panels along an axis generally perpendicular to the generally flat wall panels 26, 26, but also it allows two wall panels 26, 26 to be attached by sliding the tongues of one edge 36 into the grooves of the other edge 38 and vice-versa, without having to slide the side edge 36 of one wall panel 26 along the entire side edge 38 of the other wall panel 26. In fact, both panels may be joined with their complementary tongue and groove members through a sliding engagement that will correspond to a fraction (in this case approximately 25%) of the length of the entire panel edges 36, 38, due to the tongues 56, 60 and grooves 58, 62 that extend themselves for only a fraction of the length of the corresponding first and second edges 36, 38 on which they are formed.

The upright portion 30 of each wall panel 26 also comprises at its bottom end 35 a base 64 with a foot member 66 (see FIGS. 1 and 7) of adjustable length that is extendable away from base 64 in a direction opposite top end 33, and retractable towards base 64. More particularly, foot member 66 threadingly engages base 64 and can thus be screwed or unscrewed to adjust its length. Concrete 68 is poured over foot member 66 once the proper height is set for wall panel 26 (FIG. 1).

Swimming pool 20 also conventionally includes a flexible sheet 70 that can be made for example of vinyl. Sheet 70 is attached along its peripheral edge to a bracket 72 that engages the upper end of the upright portion of each wall pane 26 (see FIG. 6), and extends within the pool enclosure.

According to the present invention, the shelf portion 40 of the walls panels 26 is used to support one side edge of a concrete deck slab 74. The opposite side edge of the concrete deck slab is to be supported by the untouched, naturally compacted ground G beyond dugout 24, as shown in FIG. 1. One important, unexpected and advantageous result obtained with this type of pool construction, is that no distinct transverse brace is required to support the deck. This is brought about by the fact that the wall panel is narrower than the prior art combinations of a wall panel with a transverse brace, which allows the dugout itself to be narrower, which in turn allows the deck slab 74 to extend onto the untouched, naturally compacted ground. Consequently, the deck slab 74 is partly supported by the ground itself, which allows the modular wall structure 22 to be devoid of any transverse support brace.

It is noted that, as noted hereinabove, wall panels 26 might differ from one another in some aspects. For example, FIG. 2 shows a series of edgewisely interlocked wall panels 26, where wall panel 26 a is slightly larger than some other wall panels 26, includes a filter opening 28 and does not include a shelf portion 40 since a top filter opening (now shown) will be provided on the deck to allow access into the pool filter; wall panel 26 b (also shown in FIG. 7) is also slightly larger than some other wall panels 26, and includes a central hole for an air pipe; wall panels 26 c, 26 d are narrower than wall panels 26 a, 26 b, and are curved; and wall panel 26 e is also narrower than wall panels 26 a, 26 b, and is straight. Other wall panel configurations that are not illustrated in the annexed drawings can also be envisioned to accommodate different pool structures, configurations or equipment, including for example stairs and pool ladders. 

1. A modular wall structure for underground swimming pools comprising a number of wall panels each comprising: an upright portion defining opposite inner and outer sides, opposite first and second edges and opposite top and bottom ends; a shelf portion generally perpendicular to said upright portion and attached thereto at said top end in cantilevered fashion; an inclined bracing portion linking said outer side of said upright portion to said shelf portion in an inclined fashion; and complementary attachment members provided on said upright portion first and second edges to allow said wall panel to be edgewisely attached at its first edge to the second edge of an adjacent said wall panel and along its second edge to the first edge of an adjacent said wall panel.
 2. A modular wall structure as defined in claim 1, wherein at least some of said wall panels are hollow for allowing concrete to be poured therein.
 3. A modular wall structure as defined in claim 1, wherein said shelf and upright portions are not integrally linked, but are attached to each other, with said shelf portion resting against said upright portion along an inclined abutment surface transversal to said bracing portion, with said bracing portion being formed in part by a wall of said upright portion and in part by a wall of said shelf portion.
 4. A modular wall structure as defined in claim 1, wherein said complementary attachment members comprise interlocking tongue and groove members comprising a first tongue on said first edge and a first groove on said second edge complementary to said first tongue, whereby said first tongue of one said wall panel can be inserted in said first groove of another said wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said first groove retaining said first tongue for preventing said one and another wall panels thus attached to each other from being pulled apart.
 5. A modular wall structure as defined in claim 4, wherein said tongue and groove members further comprise a second tongue on said second edge and a second groove on said first edge complementary to said second tongue, whereby said second tongue of said one wall panel can be inserted in said second groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said second groove retaining said second tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 6. A modular wall structure as defined in claim 5, wherein said tongue and groove members further comprise: a third tongue on said first edge and a third groove on said second edge complementary to said third tongue, whereby said third tongue of said one wall panel can be inserted in said third groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said third groove retaining said third tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; and a fourth tongue on said second edge and a fourth groove on said first edge complementary to said fourth tongue, whereby said fourth tongue of said one wall panel can be inserted in said fourth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said fourth groove retaining said fourth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 7. A modular wall structure as defined in claim 6, wherein said first and second tongues are inwardly-oriented, said first and second grooves are outwardly-opened, said third and fourth tongues are outwardly-oriented and said third and fourth grooves are inwardly-opened.
 8. A modular wall structure as defined in claim 7, wherein said tongue and groove members further comprise: a fifth inwardly-oriented tongue on said first edge and a fifth outwardly-opened groove on said second edge complementary to said fifth tongue, whereby said fifth tongue of said one wall panel can be inserted in said fifth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said fifth groove retaining said fifth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; and a sixth inwardly-oriented tongue on said second edge and a sixth outwardly-opened groove on said first edge complementary to said sixth tongue, whereby said sixth tongue of said one wall panel can be inserted in said sixth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said sixth groove retaining said sixth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 9. A modular wall structure as defined in claim 8, wherein said first and fifth tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said first and fifth grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said second and sixth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, and said second and sixth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge.
 10. A modular wall structure as defined in claim 9, wherein said tongue and groove members further comprise: a seventh outwardly-oriented tongue on said first edge and a seventh inwardly-opened groove on said second edge complementary to said seventh tongue, whereby said seventh tongue of said one wall panel can be inserted in said seventh groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said seventh groove retaining said seventh tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; and an eighth outwardly-oriented tongue on said second edge and an eighth inwardly-opened groove on said first edge complementary to said eighth tongue, whereby said eighth tongue of said one wall panel can be inserted in said eighth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said eighth groove retaining said eighth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 11. A modular wall structure as defined in claim 10, wherein said third and seventh tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said third and seventh grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said fourth and eighth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, and said fourth and eighth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge.
 12. A modular wall structure as defined in claim 1, wherein said upright portion of each said wall panels comprises at said bottom end a base with a foot member of adjustable length that is extendable away from and retractable towards said base in a direction opposite said top end.
 13. A modular wall structure as defined in claim 12, wherein said foot member threadingly engages said base and can thus be screwed or unscrewed to adjust its length.
 14. A modular wall structure as defined in claim 1, further comprising a filter wall panel comprising: a filter panel upright portion defining opposite inner and outer sides, opposite first and second edges and opposite top and bottom ends; a top clearance at said top end for allowing a filter to be installed near said top end; a filter opening extending through said filter wall panel near said top end; and complementary attachment members provided on said filter panel upright portion first and second edges to allow said filter wall panel to be edgewisely attached at its first edge to the second edge of an adjacent said wall panel and along its second edge to the first edge of an adjacent said wall panel.
 15. An underground swimming pool comprising a modular wall structure comprising a number of wall panels each comprising: an upright portion defining opposite inner and outer sides, opposite first and second edges and opposite top and bottom ends; complementary attachment members provided on said upright portion first and second edges to allow said wall panel to be edgewisely attached at its first edge to the second edge of an adjacent said wall panel and along its second edge to the first edge of an adjacent said wall panel, whereby all said wall panels are consecutively edgewisely attached to form a continuous peripheral wall of said swimming pool; and an inner chamber at least partly filled with concrete; wherein at least some of said wall panels further comprise: a shelf portion generally perpendicular to said upright portion and attached thereto at said top end in cantilevered fashion; and an inclined bracing portion linking said outer side of said upright portion to said shelf portion in an inclined fashion; said swimming pool further comprising a flexible sheet carried by said peripheral wall and extending within said peripheral wall to form an enclosure for containing water, and a deck comprising a number of deck slabs, at least some of said deck slabs being at least partly supported by said shelf portions and extending away from said modular wall structure for being partly supported on the ground.
 16. An underground swimming pool as defined in claim 15, wherein said complementary attachment members comprise interlocking tongue and groove members comprising a first tongue on said first edge and a first groove on said second edge complementary to said first tongue, whereby said first tongue of one said wall panel can be inserted in said first groove of another said wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said first groove retaining said first tongue for preventing said one and another wall panels thus attached to each other from being pulled apart.
 17. An underground swimming pool as defined in claim 16, wherein said tongue and groove members further comprise a second tongue on said second edge and a second groove on said first edge complementary to said second tongue, whereby said second tongue of said one wall panel can be inserted in said second groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said second groove retaining said second tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 18. An underground swimming pool as defined in claim 17, wherein said tongue and groove members further comprise: a third tongue on said first edge and a third groove on said second edge complementary to said third tongue, whereby said third tongue of said one wall panel can be inserted in said third groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said third groove retaining said third tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; and a fourth tongue on said second edge and a fourth groove on said first edge complementary to said fourth tongue, whereby said fourth tongue of said one wall panel can be inserted in said fourth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said fourth groove retaining said fourth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart.
 19. An underground swimming pool as defined in claim 18, wherein said first and second tongues are inwardly-oriented, said first and second grooves are outwardly-opened, said third and fourth tongues are outwardly-oriented and said third and fourth grooves are inwardly-opened.
 20. An underground swimming pool as defined in claim 19, wherein said tongue and groove members further comprise: a fifth inwardly-oriented tongue on said first edge and a fifth outwardly-opened groove on said second edge complementary to said fifth tongue, whereby said fifth tongue of said one wall panel can be inserted in said fifth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said fifth groove retaining said fifth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; a sixth inwardly-oriented tongue on said second edge and a sixth outwardly-opened groove on said first edge complementary to said sixth tongue, whereby said sixth tongue of said one wall panel can be inserted in said sixth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said sixth groove retaining said sixth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; a seventh outwardly-oriented tongue on said first edge and a seventh inwardly-opened groove on said second edge complementary to said seventh tongue, whereby said seventh tongue of said one wall panel can be inserted in said seventh groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said seventh groove retaining said seventh tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; and an eighth outwardly-oriented tongue on said second edge and an eighth inwardly-opened groove on said first edge complementary to said eighth tongue, whereby said eighth tongue of said one wall panel can be inserted in said eighth groove of said another wall panel when said first edge of said one wall panel is disposed side-by-side with said second edge of said another wall panel, with said eighth groove retaining said eighth tongue for further preventing said one and another wall panels thus attached to each other from being pulled apart; wherein said first and fifth tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said first and fifth grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said second and sixth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said second and sixth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said third and seventh tongues extend for a fraction of the length of said first edge and are longitudinally offset along said first edge, said third and seventh grooves extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, said fourth and eighth tongues extend for a fraction of the length of said second edge and are longitudinally offset along said second edge, and said fourth and eighth grooves extend for a fraction of the length of said first edge and are longitudinally offset along said first edge. 